A humidity sensitive composition is disclosed in U.S. Pat. No. 6,693,148 which includes perlite or vermiculite in combination with a zeolite and a super absorbent polymer. The composition is usually contained in pads, mats or filters and adsorb and absorb water and increase in mass when δaw (air-device) are positive and desorb water, decreasing mass, when δaw (air-device) are negative.
Humidity causes problems in the transportation of goods in containers. In the transportation of fabrics water staining can occur due to the formation of water inside the containers including the problem of “container rain”.
The humidity sensitive compositions also release water vapour and this can be used to carry and disperse microbiostatic or microbiocidal agents . The rate of release is however difficult to control.
The extraction of small gaseous molecules and there storage is of current concern. These include but are not limited to alkanes (ethane, propane and butane), the latter two of which are combusted to provide heat, chlorofluorocarbons (CFC's), which are refrigeration gases, CO2, the product of combustion of carbon sources (e.g. wood, oil and coal), or of aerobic respiration and anaerobic fermentation, methane or marsh gas, the principal carbon product of anoxic (anaerobic) microbial growth and proliferation, methyl bromide and carbon disulfide used as fumigants, particularly of grains. Other gases can be consistently grouped as “hydrides” e.g. H2S, hydrogen sulfide (rotten egg gas), PH3, phosphine; HCN, hydrogen cyanide, which are toxic and poisonous; and “oxides”, e.g. oxygen (O2), ozone (O3), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen dioxide (NO2). The last three of these plus methane and the CFC's are the greenhouse gases which have been implicated in global warming.
Control of some gases of low molecular weight is required in food preservation and quality retention. Ethylene is a gas which is produced in nearly all climacteric tropical fruits as an endogenous ripening agent. Carbon dioxide (CO2), the product of aerobic respiration, is an effector of quality in pomes (apples, pears, etc.), fruits which are stored under refrigeration for up to now 12 months. Modified roots and tubers with high respiration rates (i.e. release of CO2—e.g. carrots, sweet potatoes, turnips, parsnips, swedes etc.) require special absorbent packaging is used. Sulphur dioxide (SO2), which is a preservative in a range of food products where it is permitted, e.g. in fruits both fresh and dried, is also used.
It is an object of this invention to address these problems.